An email sent by a subcontractor suggests that Hillary Clinton’s deputies repeatedly directed them to erase months-old backups of her State Department emails, just as federal officials began asking for the emails. The email was described Tuesday, in a letter sent by Senator Sen. Ron Johnson (R-WI)66% , the chairman of the Homeland Security and Governmental Affairs committee. Johnson’s letter outlines the complicated arrangement between Hillary Clinton’s operating company, Clinton Executive Services Corp. and its computer-server subcontractor, Platte River Networks. The Platte River subcontractor used a email backup device operated by another firm, Datto. Johnson writes: “It also appears [Platte...